1. Field of the Invention
This invention is in the field of game rackets made from high modulus material such as graphite embedded in the matrix of an epoxy resin characterized by providing a smooth transition in stiffness between various portions of the racket. The lack of abrupt changes in stiffness, as are normally present in conventional rackets, for example, produces a better feel in play. The smooth transition of stiffness results in a racket of more uniform strength.
2. Description of the Prior Art
The emphasis in recent years has been the provision of tennis rackets made from metals such as aluminum or steel. Since such metal rackets are commonly formed by extrusion or drawing, the rackets must have a substantially uniform cross-section throughout. This means that for the racket to have a sufficient strength at the handle, the cross-section must be reasonably large. Yet, the large cross-section is neither needed nor desirable at other portions of the racket. The large cross-section, of course, contributes substantially to the weight which means that little, if any, weight can be added where it would do the most good, namely, to increase the mass moment of of inertia of the racket about its longitudinal axis in the stringing plane.
Numerous tennis racket designers have recognized the desirability of positioning weights in an area in which the weights would increase the roll moment of inertia, i.e., the moment of inertia about the longitudinal axis. Typical examples of such disclosures will be found in British Pat. No. 132,698 of 1919; British Pat. No. 310,556 of 1929; and Canadian Pat. No. 848,826. An adjustably positionable set of weights for a tennis racket is disclosed in U.S. Pat. No. 3,913,911.
Still another means for increasing the rotational moment of inertia about the longitudinal axis of the racket is suggested in U.S. Pat. No. 3,801,099 which deals with a racket whose long axis is transverse to the axis of the racket handle.